Turbocharger systems can significantly increase the power output and efficiency of an internal combustion engine without significantly increasing the weight of the engine. Various turbocharger systems have been designed to provide boost to the engine over a range of operating conditions, most of these are well known in the industry. However, under certain operating conditions, such as an over-speed condition, the turbocharger may degrade and even fail due to the excessive stresses placed on various components in the turbocharger, such as the compressor and turbine blades, when the turbocharger speed has exceeded a threshold value.
In US 2006/0005540, the speed of a turbocharger is limited in an attempt to avoid turbocharger over-speed conditions, thereby reducing wear on the turbocharger as well as the likelihood of turbocharger failure. In particular, the rotational speed of the turbocharger may be limited based on combinations of pressure, temperature, and other operating conditions at the inlet of the compressor. Other attempts have been made to increase the size and therefore strength of the compressor or turbine blades to avoid degradation and possible failure of the turbocharger.
However, there may be other operating conditions during which the turbocharger system may experience high stress, resulting in degradation of the turbocharger. For example, the turbocharger system may have various resonant frequencies corresponding to the vibrational characteristics of the system. The resonant frequencies may be within the range of turbocharger operation, thereby driving unwanted oscillations having undesired amplitudes within the turbocharger. It may be difficult to provide dampening within the turbocharger system without decreasing the turbocharger's performance, reliability, and/or durability. Furthermore, when the size of the turbine or compressor blades are increased the efficiency and transient response of the turbocharger may be decreased.
A method for operation of an engine including a turbocharger system is provided. The method includes adjusting turbocharger rotational acceleration or deceleration in response to one or more known resonant frequencies. Additionally in some examples, the method may further include increasing turbocharger rotation speed in response to one or more resonant frequencies during a first condition, and increasing turbocharger deceleration in response to one or more resonant frequencies during a second condition, the second condition different from the first condition. In this way, the operating interval within one or more resonant frequency bands may be reduced thereby decreasing the oscillations within the turbocharger, decreasing the stress experienced by the turbocharger's components and therefore increasing the longevity of the turbocharger.
It should be understood that the background and summary above is provided to introduce in simplified form a selection of concepts that are further laid out in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.